By using the following reactions, calculate the heat of combustion of pentane:

C5H12 (g) + 8O2 (g) → 5CO2 (g) + 6H2O (l).

C (s) + O2 (g) → CO2 (g), ΔH = - 395 kJ

H2 (g) + 1/2O2 (g) → H2O (l), ΔH = - 285 kJ

5C (s) + 6H2 (g) → C5H12 (g), ΔH = - 147 kJ

-6.80 * 103 kJ

-2.85 * 103 kJ

-5.42 * 103 kJ

-3.54 * 103 kJ

Question

Kadyn Wu

Chemistry

26 September, 02:17

By using the following reactions, calculate the heat of combustion of pentane:

C5H12 (g) + 8O2 (g) → 5CO2 (g) + 6H2O (l).

C (s) + O2 (g) → CO2 (g), ΔH = - 395 kJ

H2 (g) + 1/2O2 (g) → H2O (l), ΔH = - 285 kJ

5C (s) + 6H2 (g) → C5H12 (g), ΔH = - 147 kJ

-6.80 * 103 kJ

-2.85 * 103 kJ

-5.42 * 103 kJ

-3.54 * 103 kJ

+4

Answers (1)

Know the Answer?

Karen Green · Answer 1

To answer this problem, we use Hess' Law to calculate the overall enthalpy of the reactions. The goal is to add all the reactions such that the final reaction is C 5H12 (g) + 8O2 (g) → 5CO2 (g) + 6H2O (l) through cancellation adn multiplication. The first equation is multiplied by 5, the second one is multiplied by 6 and the third one is reversed. The final answer is - 3538 J or - 3.54 x10^3 kJ.